separate en/decoder specific parts from png.c

Originally committed as revision 9686 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 13 insertions, 859 deletions

diff --git a/libavcodec/png.c b/libavcodec/png.c
index 5f9b1cdccd..2af7700630 100644
--- a/libavcodec/png.c
+++ b/libavcodec/png.c
@@ -20,127 +20,43 @@
  */
 #include "avcodec.h"
 #include "bytestream.h"
+#include "png.h"
 
-/* TODO:
- * - add 2, 4 and 16 bit depth support
- * - use filters when generating a png (better compression)
- */
-
-#include <zlib.h>
-
-//#define DEBUG
-
-#define PNG_COLOR_MASK_PALETTE    1
-#define PNG_COLOR_MASK_COLOR      2
-#define PNG_COLOR_MASK_ALPHA      4
-
-#define PNG_COLOR_TYPE_GRAY 0
-#define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
-#define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
-#define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
-#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
-
-#define PNG_FILTER_VALUE_NONE  0
-#define PNG_FILTER_VALUE_SUB   1
-#define PNG_FILTER_VALUE_UP    2
-#define PNG_FILTER_VALUE_AVG   3
-#define PNG_FILTER_VALUE_PAETH 4
-
-#define PNG_IHDR      0x0001
-#define PNG_IDAT      0x0002
-#define PNG_ALLIMAGE  0x0004
-#define PNG_PLTE      0x0008
-
-#define NB_PASSES 7
-
-#define IOBUF_SIZE 4096
-
-typedef struct PNGContext {
-    uint8_t *bytestream;
-    uint8_t *bytestream_start;
-    uint8_t *bytestream_end;
-    AVFrame picture;
-
-    int state;
-    int width, height;
-    int bit_depth;
-    int color_type;
-    int compression_type;
-    int interlace_type;
-    int filter_type;
-    int channels;
-    int bits_per_pixel;
-    int bpp;
-
-    uint8_t *image_buf;
-    int image_linesize;
-    uint32_t palette[256];
-    uint8_t *crow_buf;
-    uint8_t *last_row;
-    uint8_t *tmp_row;
-    int pass;
-    int crow_size; /* compressed row size (include filter type) */
-    int row_size; /* decompressed row size */
-    int pass_row_size; /* decompress row size of the current pass */
-    int y;
-    z_stream zstream;
-    uint8_t buf[IOBUF_SIZE];
-} PNGContext;
-
-static const uint8_t pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+const uint8_t ff_pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 
 /* Mask to determine which y pixels are valid in a pass */
-static const uint8_t png_pass_ymask[NB_PASSES] = {
+const uint8_t ff_png_pass_ymask[NB_PASSES] = {
     0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55,
 };
 
-/* Mask to determine which y pixels can be written in a pass */
-static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
-    0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
-};
-
 /* minimum x value */
-static const uint8_t png_pass_xmin[NB_PASSES] = {
+const uint8_t ff_png_pass_xmin[NB_PASSES] = {
     0, 4, 0, 2, 0, 1, 0
 };
 
 /* x shift to get row width */
-static const uint8_t png_pass_xshift[NB_PASSES] = {
+const uint8_t ff_png_pass_xshift[NB_PASSES] = {
     3, 3, 2, 2, 1, 1, 0
 };
 
 /* Mask to determine which pixels are valid in a pass */
-static const uint8_t png_pass_mask[NB_PASSES] = {
+const uint8_t ff_png_pass_mask[NB_PASSES] = {
     0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff
 };
 
-/* Mask to determine which pixels to overwrite while displaying */
-static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
-    0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
-};
-#if 0
-static int png_probe(AVProbeData *pd)
-{
-    if (pd->buf_size >= 8 &&
-        memcmp(pd->buf, pngsig, 8) == 0)
-        return AVPROBE_SCORE_MAX;
-    else
-        return 0;
-}
-#endif
-static void *png_zalloc(void *opaque, unsigned int items, unsigned int size)
+void *ff_png_zalloc(void *opaque, unsigned int items, unsigned int size)
 {
     if(items >= UINT_MAX / size)
         return NULL;
     return av_malloc(items * size);
 }
 
-static void png_zfree(void *opaque, void *ptr)
+void ff_png_zfree(void *opaque, void *ptr)
 {
     av_free(ptr);
 }
 
-static int png_get_nb_channels(int color_type)
+int ff_png_get_nb_channels(int color_type)
 {
     int channels;
     channels = 1;
@@ -153,580 +69,19 @@ static int png_get_nb_channels(int color_type)
 }
 
 /* compute the row size of an interleaved pass */
-static int png_pass_row_size(int pass, int bits_per_pixel, int width)
+int ff_png_pass_row_size(int pass, int bits_per_pixel, int width)
 {
     int shift, xmin, pass_width;
 
-    xmin = png_pass_xmin[pass];
+    xmin = ff_png_pass_xmin[pass];
     if (width <= xmin)
         return 0;
-    shift = png_pass_xshift[pass];
+    shift = ff_png_pass_xshift[pass];
     pass_width = (width - xmin + (1 << shift) - 1) >> shift;
     return (pass_width * bits_per_pixel + 7) >> 3;
 }
 
-/* NOTE: we try to construct a good looking image at each pass. width
-   is the original image width. We also do pixel format convertion at
-   this stage */
-static void png_put_interlaced_row(uint8_t *dst, int width,
-                                   int bits_per_pixel, int pass,
-                                   int color_type, const uint8_t *src)
-{
-    int x, mask, dsp_mask, j, src_x, b, bpp;
-    uint8_t *d;
-    const uint8_t *s;
-
-    mask = png_pass_mask[pass];
-    dsp_mask = png_pass_dsp_mask[pass];
-    switch(bits_per_pixel) {
-    case 1:
-        /* we must initialize the line to zero before writing to it */
-        if (pass == 0)
-            memset(dst, 0, (width + 7) >> 3);
-        src_x = 0;
-        for(x = 0; x < width; x++) {
-            j = (x & 7);
-            if ((dsp_mask << j) & 0x80) {
-                b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
-                dst[x >> 3] |= b << (7 - j);
-            }
-            if ((mask << j) & 0x80)
-                src_x++;
-        }
-        break;
-    default:
-        bpp = bits_per_pixel >> 3;
-        d = dst;
-        s = src;
-        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
-            for(x = 0; x < width; x++) {
-                j = x & 7;
-                if ((dsp_mask << j) & 0x80) {
-                    *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
-                }
-                d += bpp;
-                if ((mask << j) & 0x80)
-                    s += bpp;
-            }
-        } else {
-            for(x = 0; x < width; x++) {
-                j = x & 7;
-                if ((dsp_mask << j) & 0x80) {
-                    memcpy(d, s, bpp);
-                }
-                d += bpp;
-                if ((mask << j) & 0x80)
-                    s += bpp;
-            }
-        }
-        break;
-    }
-}
-
-#ifdef CONFIG_ENCODERS
-static void png_get_interlaced_row(uint8_t *dst, int row_size,
-                                   int bits_per_pixel, int pass,
-                                   const uint8_t *src, int width)
-{
-    int x, mask, dst_x, j, b, bpp;
-    uint8_t *d;
-    const uint8_t *s;
-
-    mask = png_pass_mask[pass];
-    switch(bits_per_pixel) {
-    case 1:
-        memset(dst, 0, row_size);
-        dst_x = 0;
-        for(x = 0; x < width; x++) {
-            j = (x & 7);
-            if ((mask << j) & 0x80) {
-                b = (src[x >> 3] >> (7 - j)) & 1;
-                dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
-                dst_x++;
-            }
-        }
-        break;
-    default:
-        bpp = bits_per_pixel >> 3;
-        d = dst;
-        s = src;
-        for(x = 0; x < width; x++) {
-            j = x & 7;
-            if ((mask << j) & 0x80) {
-                memcpy(d, s, bpp);
-                d += bpp;
-            }
-            s += bpp;
-        }
-        break;
-    }
-}
-#endif
-
-/* XXX: optimize */
-/* NOTE: 'dst' can be equal to 'last' */
-static void png_filter_row(uint8_t *dst, int filter_type,
-                           uint8_t *src, uint8_t *last, int size, int bpp)
-{
-    int i, p;
-
-    switch(filter_type) {
-    case PNG_FILTER_VALUE_NONE:
-        memcpy(dst, src, size);
-        break;
-    case PNG_FILTER_VALUE_SUB:
-        for(i = 0; i < bpp; i++) {
-            dst[i] = src[i];
-        }
-        for(i = bpp; i < size; i++) {
-            p = dst[i - bpp];
-            dst[i] = p + src[i];
-        }
-        break;
-    case PNG_FILTER_VALUE_UP:
-        for(i = 0; i < size; i++) {
-            p = last[i];
-            dst[i] = p + src[i];
-        }
-        break;
-    case PNG_FILTER_VALUE_AVG:
-        for(i = 0; i < bpp; i++) {
-            p = (last[i] >> 1);
-            dst[i] = p + src[i];
-        }
-        for(i = bpp; i < size; i++) {
-            p = ((dst[i - bpp] + last[i]) >> 1);
-            dst[i] = p + src[i];
-        }
-        break;
-    case PNG_FILTER_VALUE_PAETH:
-        for(i = 0; i < bpp; i++) {
-            p = last[i];
-            dst[i] = p + src[i];
-        }
-        for(i = bpp; i < size; i++) {
-            int a, b, c, pa, pb, pc;
-
-            a = dst[i - bpp];
-            b = last[i];
-            c = last[i - bpp];
-
-            p = b - c;
-            pc = a - c;
-
-            pa = abs(p);
-            pb = abs(pc);
-            pc = abs(p + pc);
-
-            if (pa <= pb && pa <= pc)
-                p = a;
-            else if (pb <= pc)
-                p = b;
-            else
-                p = c;
-            dst[i] = p + src[i];
-        }
-        break;
-    }
-}
-
-#ifdef CONFIG_ENCODERS
-static void convert_from_rgb32(uint8_t *dst, const uint8_t *src, int width)
-{
-    uint8_t *d;
-    int j;
-    unsigned int v;
-
-    d = dst;
-    for(j = 0; j < width; j++) {
-        v = ((const uint32_t *)src)[j];
-        d[0] = v >> 16;
-        d[1] = v >> 8;
-        d[2] = v;
-        d[3] = v >> 24;
-        d += 4;
-    }
-}
-#endif
-
-#ifdef CONFIG_DECODERS
-static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width)
-{
-    int j;
-    unsigned int r, g, b, a;
-
-    for(j = 0;j < width; j++) {
-        r = src[0];
-        g = src[1];
-        b = src[2];
-        a = src[3];
-        *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
-        dst += 4;
-        src += 4;
-    }
-}
-
-/* process exactly one decompressed row */
-static void png_handle_row(PNGContext *s)
-{
-    uint8_t *ptr, *last_row;
-    int got_line;
-
-    if (!s->interlace_type) {
-        ptr = s->image_buf + s->image_linesize * s->y;
-        /* need to swap bytes correctly for RGB_ALPHA */
-        if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
-            png_filter_row(s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
-                           s->last_row, s->row_size, s->bpp);
-            memcpy(s->last_row, s->tmp_row, s->row_size);
-            convert_to_rgb32(ptr, s->tmp_row, s->width);
-        } else {
-            /* in normal case, we avoid one copy */
-            if (s->y == 0)
-                last_row = s->last_row;
-            else
-                last_row = ptr - s->image_linesize;
-
-            png_filter_row(ptr, s->crow_buf[0], s->crow_buf + 1,
-                           last_row, s->row_size, s->bpp);
-        }
-        s->y++;
-        if (s->y == s->height) {
-            s->state |= PNG_ALLIMAGE;
-        }
-    } else {
-        got_line = 0;
-        for(;;) {
-            ptr = s->image_buf + s->image_linesize * s->y;
-            if ((png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
-                /* if we already read one row, it is time to stop to
-                   wait for the next one */
-                if (got_line)
-                    break;
-                png_filter_row(s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
-                               s->last_row, s->pass_row_size, s->bpp);
-                memcpy(s->last_row, s->tmp_row, s->pass_row_size);
-                got_line = 1;
-            }
-            if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
-                /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
-                png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
-                                       s->color_type, s->last_row);
-            }
-            s->y++;
-            if (s->y == s->height) {
-                for(;;) {
-                    if (s->pass == NB_PASSES - 1) {
-                        s->state |= PNG_ALLIMAGE;
-                        goto the_end;
-                    } else {
-                        s->pass++;
-                        s->y = 0;
-                        s->pass_row_size = png_pass_row_size(s->pass,
-                                                             s->bits_per_pixel,
-                                                             s->width);
-                        s->crow_size = s->pass_row_size + 1;
-                        if (s->pass_row_size != 0)
-                            break;
-                        /* skip pass if empty row */
-                    }
-                }
-            }
-        }
-    the_end: ;
-    }
-}
-
-static int png_decode_idat(PNGContext *s, int length)
-{
-    int ret;
-    s->zstream.avail_in = length;
-    s->zstream.next_in = s->bytestream;
-    s->bytestream += length;
-
-    if(s->bytestream > s->bytestream_end)
-        return -1;
-
-    /* decode one line if possible */
-    while (s->zstream.avail_in > 0) {
-        ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
-        if (ret != Z_OK && ret != Z_STREAM_END) {
-            return -1;
-        }
-        if (s->zstream.avail_out == 0) {
-            if (!(s->state & PNG_ALLIMAGE)) {
-                png_handle_row(s);
-            }
-            s->zstream.avail_out = s->crow_size;
-            s->zstream.next_out = s->crow_buf;
-        }
-    }
-    return 0;
-}
-
-static int decode_frame(AVCodecContext *avctx,
-                        void *data, int *data_size,
-                        uint8_t *buf, int buf_size)
-{
-    PNGContext * const s = avctx->priv_data;
-    AVFrame *picture = data;
-    AVFrame * const p= (AVFrame*)&s->picture;
-    uint32_t tag, length;
-    int ret, crc;
-
-    s->bytestream_start=
-    s->bytestream= buf;
-    s->bytestream_end= buf + buf_size;
-
-    /* check signature */
-    if (memcmp(s->bytestream, pngsig, 8) != 0)
-        return -1;
-    s->bytestream+= 8;
-    s->y=
-    s->state=0;
-//    memset(s, 0, sizeof(PNGContext));
-    /* init the zlib */
-    s->zstream.zalloc = png_zalloc;
-    s->zstream.zfree = png_zfree;
-    s->zstream.opaque = NULL;
-    ret = inflateInit(&s->zstream);
-    if (ret != Z_OK)
-        return -1;
-    for(;;) {
-        int tag32;
-        if (s->bytestream >= s->bytestream_end)
-            goto fail;
-        length = bytestream_get_be32(&s->bytestream);
-        if (length > 0x7fffffff)
-            goto fail;
-        tag32 = bytestream_get_be32(&s->bytestream);
-        tag = bswap_32(tag32);
-#ifdef DEBUG
-        av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
-               (tag & 0xff),
-               ((tag >> 8) & 0xff),
-               ((tag >> 16) & 0xff),
-               ((tag >> 24) & 0xff), length);
-#endif
-        switch(tag) {
-        case MKTAG('I', 'H', 'D', 'R'):
-            if (length != 13)
-                goto fail;
-            s->width = bytestream_get_be32(&s->bytestream);
-            s->height = bytestream_get_be32(&s->bytestream);
-            if(avcodec_check_dimensions(avctx, s->width, s->height)){
-                s->width= s->height= 0;
-                goto fail;
-            }
-            s->bit_depth = *s->bytestream++;
-            s->color_type = *s->bytestream++;
-            s->compression_type = *s->bytestream++;
-            s->filter_type = *s->bytestream++;
-            s->interlace_type = *s->bytestream++;
-            crc = bytestream_get_be32(&s->bytestream);
-            s->state |= PNG_IHDR;
-#ifdef DEBUG
-            av_log(avctx, AV_LOG_DEBUG, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
-                   s->width, s->height, s->bit_depth, s->color_type,
-                   s->compression_type, s->filter_type, s->interlace_type);
-#endif
-            break;
-        case MKTAG('I', 'D', 'A', 'T'):
-            if (!(s->state & PNG_IHDR))
-                goto fail;
-            if (!(s->state & PNG_IDAT)) {
-                /* init image info */
-                avctx->width = s->width;
-                avctx->height = s->height;
-
-                s->channels = png_get_nb_channels(s->color_type);
-                s->bits_per_pixel = s->bit_depth * s->channels;
-                s->bpp = (s->bits_per_pixel + 7) >> 3;
-                s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
-
-                if (s->bit_depth == 8 &&
-                    s->color_type == PNG_COLOR_TYPE_RGB) {
-                    avctx->pix_fmt = PIX_FMT_RGB24;
-                } else if (s->bit_depth == 8 &&
-                           s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
-                    avctx->pix_fmt = PIX_FMT_RGB32;
-                } else if (s->bit_depth == 8 &&
-                           s->color_type == PNG_COLOR_TYPE_GRAY) {
-                    avctx->pix_fmt = PIX_FMT_GRAY8;
-                } else if (s->bit_depth == 16 &&
-                           s->color_type == PNG_COLOR_TYPE_GRAY) {
-                    avctx->pix_fmt = PIX_FMT_GRAY16BE;
-                } else if (s->bit_depth == 1 &&
-                           s->color_type == PNG_COLOR_TYPE_GRAY) {
-                    avctx->pix_fmt = PIX_FMT_MONOBLACK;
-                } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
-                    avctx->pix_fmt = PIX_FMT_PAL8;
-                } else {
-                    goto fail;
-                }
-                if(p->data[0])
-                    avctx->release_buffer(avctx, p);
-
-                p->reference= 0;
-                if(avctx->get_buffer(avctx, p) < 0){
-                    av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-                    goto fail;
-                }
-                p->pict_type= FF_I_TYPE;
-                p->key_frame= 1;
-                p->interlaced_frame = !!s->interlace_type;
-
-                /* compute the compressed row size */
-                if (!s->interlace_type) {
-                    s->crow_size = s->row_size + 1;
-                } else {
-                    s->pass = 0;
-                    s->pass_row_size = png_pass_row_size(s->pass,
-                                                         s->bits_per_pixel,
-                                                         s->width);
-                    s->crow_size = s->pass_row_size + 1;
-                }
-#ifdef DEBUG
-                av_log(avctx, AV_LOG_DEBUG, "row_size=%d crow_size =%d\n",
-                       s->row_size, s->crow_size);
-#endif
-                s->image_buf = p->data[0];
-                s->image_linesize = p->linesize[0];
-                /* copy the palette if needed */
-                if (s->color_type == PNG_COLOR_TYPE_PALETTE)
-                    memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
-                /* empty row is used if differencing to the first row */
-                s->last_row = av_mallocz(s->row_size);
-                if (!s->last_row)
-                    goto fail;
-                if (s->interlace_type ||
-                    s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
-                    s->tmp_row = av_malloc(s->row_size);
-                    if (!s->tmp_row)
-                        goto fail;
-                }
-                /* compressed row */
-                s->crow_buf = av_malloc(s->row_size + 1);
-                if (!s->crow_buf)
-                    goto fail;
-                s->zstream.avail_out = s->crow_size;
-                s->zstream.next_out = s->crow_buf;
-            }
-            s->state |= PNG_IDAT;
-            if (png_decode_idat(s, length) < 0)
-                goto fail;
-            /* skip crc */
-            crc = bytestream_get_be32(&s->bytestream);
-            break;
-        case MKTAG('P', 'L', 'T', 'E'):
-            {
-                int n, i, r, g, b;
-
-                if ((length % 3) != 0 || length > 256 * 3)
-                    goto skip_tag;
-                /* read the palette */
-                n = length / 3;
-                for(i=0;i<n;i++) {
-                    r = *s->bytestream++;
-                    g = *s->bytestream++;
-                    b = *s->bytestream++;
-                    s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
-                }
-                for(;i<256;i++) {
-                    s->palette[i] = (0xff << 24);
-                }
-                s->state |= PNG_PLTE;
-                crc = bytestream_get_be32(&s->bytestream);
-            }
-            break;
-        case MKTAG('t', 'R', 'N', 'S'):
-            {
-                int v, i;
-
-                /* read the transparency. XXX: Only palette mode supported */
-                if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
-                    length > 256 ||
-                    !(s->state & PNG_PLTE))
-                    goto skip_tag;
-                for(i=0;i<length;i++) {
-                    v = *s->bytestream++;
-                    s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
-                }
-                crc = bytestream_get_be32(&s->bytestream);
-            }
-            break;
-        case MKTAG('I', 'E', 'N', 'D'):
-            if (!(s->state & PNG_ALLIMAGE))
-                goto fail;
-            crc = bytestream_get_be32(&s->bytestream);
-            goto exit_loop;
-        default:
-            /* skip tag */
-        skip_tag:
-            s->bytestream += length + 4;
-            break;
-        }
-    }
- exit_loop:
-    *picture= *(AVFrame*)&s->picture;
-    *data_size = sizeof(AVPicture);
-
-    ret = s->bytestream - s->bytestream_start;
- the_end:
-    inflateEnd(&s->zstream);
-    av_freep(&s->crow_buf);
-    av_freep(&s->last_row);
-    av_freep(&s->tmp_row);
-    return ret;
- fail:
-    ret = -1;
-    goto the_end;
-}
-#endif
-
-#ifdef CONFIG_ENCODERS
-static void png_write_chunk(uint8_t **f, uint32_t tag,
-                            const uint8_t *buf, int length)
-{
-    uint32_t crc;
-    uint8_t tagbuf[4];
-
-    bytestream_put_be32(f, length);
-    crc = crc32(0, Z_NULL, 0);
-    AV_WL32(tagbuf, tag);
-    crc = crc32(crc, tagbuf, 4);
-    bytestream_put_be32(f, bswap_32(tag));
-    if (length > 0) {
-        crc = crc32(crc, buf, length);
-        memcpy(*f, buf, length);
-        *f += length;
-    }
-    bytestream_put_be32(f, crc);
-}
-
-/* XXX: do filtering */
-static int png_write_row(PNGContext *s, const uint8_t *data, int size)
-{
-    int ret;
-
-    s->zstream.avail_in = size;
-    s->zstream.next_in = (uint8_t *)data;
-    while (s->zstream.avail_in > 0) {
-        ret = deflate(&s->zstream, Z_NO_FLUSH);
-        if (ret != Z_OK)
-            return -1;
-        if (s->zstream.avail_out == 0) {
-            if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
-                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
-            s->zstream.avail_out = IOBUF_SIZE;
-            s->zstream.next_out = s->buf;
-        }
-    }
-    return 0;
-}
-#endif /* CONFIG_ENCODERS */
-
-static int common_init(AVCodecContext *avctx){
+int ff_png_common_init(AVCodecContext *avctx){
     PNGContext *s = avctx->priv_data;
 
     avcodec_get_frame_defaults((AVFrame*)&s->picture);
@@ -735,204 +90,3 @@ static int common_init(AVCodecContext *avctx){
 
     return 0;
 }
-
-#ifdef CONFIG_ENCODERS
-static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
-    PNGContext *s = avctx->priv_data;
-    AVFrame *pict = data;
-    AVFrame * const p= (AVFrame*)&s->picture;
-    int bit_depth, color_type, y, len, row_size, ret, is_progressive;
-    int bits_per_pixel, pass_row_size;
-    uint8_t *ptr;
-    uint8_t *crow_buf = NULL;
-    uint8_t *tmp_buf = NULL;
-
-    *p = *pict;
-    p->pict_type= FF_I_TYPE;
-    p->key_frame= 1;
-
-    s->bytestream_start=
-    s->bytestream= buf;
-    s->bytestream_end= buf+buf_size;
-
-    is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
-    switch(avctx->pix_fmt) {
-    case PIX_FMT_RGB32:
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-        break;
-    case PIX_FMT_RGB24:
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_RGB;
-        break;
-    case PIX_FMT_GRAY8:
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_GRAY;
-        break;
-    case PIX_FMT_MONOBLACK:
-        bit_depth = 1;
-        color_type = PNG_COLOR_TYPE_GRAY;
-        break;
-    case PIX_FMT_PAL8:
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_PALETTE;
-        break;
-    default:
-        return -1;
-    }
-    bits_per_pixel = png_get_nb_channels(color_type) * bit_depth;
-    row_size = (avctx->width * bits_per_pixel + 7) >> 3;
-
-    s->zstream.zalloc = png_zalloc;
-    s->zstream.zfree = png_zfree;
-    s->zstream.opaque = NULL;
-    ret = deflateInit2(&s->zstream, Z_DEFAULT_COMPRESSION,
-                       Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
-    if (ret != Z_OK)
-        return -1;
-    crow_buf = av_malloc(row_size + 1);
-    if (!crow_buf)
-        goto fail;
-    if (is_progressive) {
-        tmp_buf = av_malloc(row_size + 1);
-        if (!tmp_buf)
-            goto fail;
-    }
-
-    /* write png header */
-    memcpy(s->bytestream, pngsig, 8);
-    s->bytestream += 8;
-
-    AV_WB32(s->buf, avctx->width);
-    AV_WB32(s->buf + 4, avctx->height);
-    s->buf[8] = bit_depth;
-    s->buf[9] = color_type;
-    s->buf[10] = 0; /* compression type */
-    s->buf[11] = 0; /* filter type */
-    s->buf[12] = is_progressive; /* interlace type */
-
-    png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
-
-    /* put the palette if needed */
-    if (color_type == PNG_COLOR_TYPE_PALETTE) {
-        int has_alpha, alpha, i;
-        unsigned int v;
-        uint32_t *palette;
-        uint8_t *alpha_ptr;
-
-        palette = (uint32_t *)p->data[1];
-        ptr = s->buf;
-        alpha_ptr = s->buf + 256 * 3;
-        has_alpha = 0;
-        for(i = 0; i < 256; i++) {
-            v = palette[i];
-            alpha = v >> 24;
-            if (alpha && alpha != 0xff)
-                has_alpha = 1;
-            *alpha_ptr++ = alpha;
-            bytestream_put_be24(&ptr, v);
-        }
-        png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
-        if (has_alpha) {
-            png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
-        }
-    }
-
-    /* now put each row */
-    s->zstream.avail_out = IOBUF_SIZE;
-    s->zstream.next_out = s->buf;
-    if (is_progressive) {
-        uint8_t *ptr1;
-        int pass;
-
-        for(pass = 0; pass < NB_PASSES; pass++) {
-            /* NOTE: a pass is completely omited if no pixels would be
-               output */
-            pass_row_size = png_pass_row_size(pass, bits_per_pixel, avctx->width);
-            if (pass_row_size > 0) {
-                for(y = 0; y < avctx->height; y++) {
-                    if ((png_pass_ymask[pass] << (y & 7)) & 0x80) {
-                        ptr = p->data[0] + y * p->linesize[0];
-                        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
-                            convert_from_rgb32(tmp_buf, ptr, avctx->width);
-                            ptr1 = tmp_buf;
-                        } else {
-                            ptr1 = ptr;
-                        }
-                        png_get_interlaced_row(crow_buf + 1, pass_row_size,
-                                               bits_per_pixel, pass,
-                                               ptr1, avctx->width);
-                        crow_buf[0] = PNG_FILTER_VALUE_NONE;
-                        png_write_row(s, crow_buf, pass_row_size + 1);
-                    }
-                }
-            }
-        }
-    } else {
-        for(y = 0; y < avctx->height; y++) {
-            ptr = p->data[0] + y * p->linesize[0];
-            if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-                convert_from_rgb32(crow_buf + 1, ptr, avctx->width);
-            else
-                memcpy(crow_buf + 1, ptr, row_size);
-            crow_buf[0] = PNG_FILTER_VALUE_NONE;
-            png_write_row(s, crow_buf, row_size + 1);
-        }
-    }
-    /* compress last bytes */
-    for(;;) {
-        ret = deflate(&s->zstream, Z_FINISH);
-        if (ret == Z_OK || ret == Z_STREAM_END) {
-            len = IOBUF_SIZE - s->zstream.avail_out;
-            if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
-                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
-            }
-            s->zstream.avail_out = IOBUF_SIZE;
-            s->zstream.next_out = s->buf;
-            if (ret == Z_STREAM_END)
-                break;
-        } else {
-            goto fail;
-        }
-    }
-    png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
-
-    ret = s->bytestream - s->bytestream_start;
- the_end:
-    av_free(crow_buf);
-    av_free(tmp_buf);
-    deflateEnd(&s->zstream);
-    return ret;
- fail:
-    ret = -1;
-    goto the_end;
-}
-#endif
-
-#ifdef CONFIG_PNG_DECODER
-AVCodec png_decoder = {
-    "png",
-    CODEC_TYPE_VIDEO,
-    CODEC_ID_PNG,
-    sizeof(PNGContext),
-    common_init,
-    NULL,
-    NULL, //decode_end,
-    decode_frame,
-    0 /*CODEC_CAP_DR1*/ /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
-    NULL
-};
-#endif
-
-#ifdef CONFIG_PNG_ENCODER
-AVCodec png_encoder = {
-    "png",
-    CODEC_TYPE_VIDEO,
-    CODEC_ID_PNG,
-    sizeof(PNGContext),
-    common_init,
-    encode_frame,
-    NULL, //encode_end,
-    .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGB32, PIX_FMT_PAL8, PIX_FMT_GRAY8, PIX_FMT_MONOBLACK, -1},
-};
-#endif // CONFIG_PNG_ENCODER